From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Preignition issues with a 25/30 unit cylinder head and the subsequent swapping of parts.
| Identifier | ExFiles\Box 107\3\ scan0060 | |
| Date | 2nd February 1937 | |
| To RHC.{R. H. Coverley - Production Engineer} from Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} c. to Mx.{John H Maddocks - Chief Proving Officer} 25/30 UNIT. We have been preparing a unit for Mx.{John H Maddocks - Chief Proving Officer}, to replace the unit which was loaned to us and fitted in Sg.{Arthur F. Sidgreaves - MD}'s car. With the cylinder head as taken from Production preignition was experienced on Nos. 2 & 3 cylinders and after a short period of full throttle running, it was possible to short the plugs (2 & 3) without any drop whatever in R.P.M. or power. Another head was borrowed from Mx.{John H Maddocks - Chief Proving Officer}, this being O.K. and has been retained on the engine which has been sent to Mx.{John H Maddocks - Chief Proving Officer} in exchange for the engine now in Sg.{Arthur F. Sidgreaves - MD}'s car. We are sending the head which has the preignition trouble to you for your inspection. If there is no apparent trouble when the core plugs are removed, it would be advisable to get it sectioned up for further investigation. This leaves Mx.{John H Maddocks - Chief Proving Officer} short of a head, will you therefore supply him with one in lieu of the head we have returned to you for your inspection. Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} | ||